GOODMAN20 "Back Off Mary Poppins" -- Charlie Sheen (left) with guest starts, (left to right) Elvis Costello and Sean Penn on TWO AND A HALF MEN Mondays, (9:30-10:00 PM, ET/PT) on the CBS Television Network.. Photo: �2004 Warner Brothers Television Inc. MANDATORY CREDIT; ; NO ARCHIVE; NORTH AMERICAN USE ONLY

Bad, good by default and strangely overlooked. Two new series and sophomore sitcom roll out and in tonight, each offering a little truism about mainstream TV comedies.

The first, CBS' ill-advised Jason Alexander vehicle, "Listen Up," proves a couple things right off the bat. First, Alexander is in a slump. Either he can't get the right material or he really is as annoying as George Costanza. Here he plays the fictional version of Washington Post sports columnist and ESPN host Tony Kornheiser and manages, against great odds, to be more grating than the original.

But also less than half as funny or engaging.

Kornheiser in print has a cult of personality, and, on TV (and radio), he puts that personality in your face by doing what he does best -- yelling. Mostly it's mock outrage, but often he's stem-wound like nobody's business. Perhaps the immediate face (and attitude) to play him was, in the casting director's mind, Alexander's. But that in itself is a sort of channeling of the "Seinfeld" character.

Here, even putting him in CBS' worn-leather-chair idea of a "family sitcom," he's more abrasive than anything else. If Kornheiser is often intolerable as himself, spouting off on a wide range of sports and pop culture topics, what gave the producers the idea that Alexander would be able to make that shtick palatable to the masses?

He can't.

And in "Listen Up" -- after 15 minutes it's more like "Tune Out" -- the whole combination of trite writing, dull supporting actors and the Alexander buzz saw of unlikeability makes this a non-starter. Malcolm-Jamal Warner is Alexander's sidekick and leaves no impression other than stray thoughts about his hair. The problem may have more to do with the material than how Warner is delivering it, but still.

There will be a lot written about the so-called "Seinfeld" curse. But there's no hex on Alexander or any of the other alums. They've simply made bad decisions about bad material. "Listen Up" is grating and poorly executed -- and last time anyone checked, those are hardly building blocks for a successful family sitcom.

More effective is UPN's "Second Time Around," a pleasantly forgettable romantic comedy that would, on any other network, qualify as just another middling offering. But this is UPN, which set the bar so low in years past it was buried with the fiber optic cables and sewer lines. This season, however, there's been a dramatic turn-around in terms of quality content at the network. So "Second Time Around" seems exponentially better when it's really just average.

This sitcom's premise is, like most others, flimsy. Two people marry -- for the second time -- and try to learn from past mistakes and build on their new maturity.

It's unclear whether there's a full season's worth of a material in that -- much less an extended run -- but the stars are real-life couple Boris Kodjoe and Nicole Parker, who met on the set of Showtime's "Soul Food," and they are very, very easy on the eyes. And yes, they have chemistry. And yes again, equally flimsy sitcoms have turned out to be decent hits. So who knows.

It's just hard to believe that the hook of the pilot -- their pasts keep coming back to haunt them -- won't become a very old joke by episode eight. But credit UPN for upping its talent level and this series will make a fine companion on Monday nights with its network lead-in, "Girlfriends."

What we learn from these two new series is fairly obvious. It's very difficult, in the case of "Listen Up," to recreate someone who is a legitimate, original character -- emphasis on character. And casting, long an overlooked culprit of failed TV shows, plays an integral part in the downfall of "Listen Up." Alexander, whether he likes it or not, has an acting style and a comic delivery that, no matter what he does, closely resembles his George Costanza character. At this point, he may need to shave his head like Michael Chiklis and get into drama.

In "Second Time Around," network personality -- something rarely talked about -- comes into play. Cynical viewers have wondered whether HBO doesn't get some special critical slack merely by being HBO. Put another way, would an HBO series on ABC, for example, meet with the same reverence (provided it could pass FCC standards, naturally)?

There may be some truth to that argument, but this much is certain: HBO earned its reputation. Sadly, so did UPN. And now that UPN is on the upswing, innocuous fair like "Second Time Around" may benefit positively from past comparisons.

Mainstream TV comedy is an interesting vocation. Smart viewers are almost always disdainful of it, but the masses are drawn to it. A lot of people think "Everybody Loves Raymond" is dumb and predictable, while conventional wisdom is that it's one of the best comedies on TV. Certainly it's no "Arrested Development," but "Raymond" may get the last laugh (again) when and if Fox dumps "Arrested Development" shortly after renewing it.

That said, the appeal for producers in a standard, old-school sitcom is that if it hits big, the sky opens up and rains down money. For all involved. As a writer or producer, you may not get the street cred of something that's slaying discerning fans on Comedy Central, but you also drive a better car and have a bigger nest egg.

It's also true that shows like "Raymond" or "Friends" or "Seinfeld" can succeed in the genre without being, by association, of lesser value than something more hip.

This is the case with "Two and a Half Men," the sophomore sitcom on CBS starring Charlie Sheen and Jon Cryer. Now, CBS does quality shows across the board -- it's a reliable brand. But its comedies will never be described as having right angles. They are uniformly soft and digestible, with no noticeable edge.

But "Two and a Half Men" is of the broadcast TV pedigree that's actually funny in that style. People scoffed at "Friends," but it was clever and wit- filled. This series, too, is funny and cleverly played each week. (Over on ABC, a case could be made for "Less Than Perfect," as well.)

Tonight, "Two and A Half Men" pulls off a great casting coup -- one that may be tough to match for anyone else all season long. The episode has Sheen's character, Charlie -- formerly hard-living, famously a bachelor -- inviting some of his friends over for a support group. Those friends are Sean Penn, Elvis Costello and Harry Dean Stanton. That, people, is crazy impressive.

The discerning Penn isn't exactly Mr. TV, Costello is a legend and Stanton could very well be this country's best (and most weathered) character actor. There's a lot of cool in that threesome.

This could be CBS' way of saying, "Hey, you know when 'Raymond' leaves next season, this right here is our go-to replacement show."

And it should be. Last season "Two and a Half Men" was considered surprisingly funny mostly because Sheen was such an unexpected comic delight, and Cryer, as his stiff, socially inept loser of a brother, finally found a hit. His talent for well-timed TV sitcom language is well-honed at this point. Even the "half," in child actor Angus T. Jones, worked well because he was never cloying or bratlike.

This is a series that deserves a second look, and with these cameos there's no better time to check it out.